The present invention relates to a prepreg sheet for flake lining and a lining process using the same.
It has already been known that flake lining characterized by using a compound comprising a matrix resin and thin flakes of, for example, glass dispersed therein is useful as corrosion-resistant lining for chemical equipment, storage facilities for petroleum, stack gas desulfurization facilities and the like. In such flake lining, flakes contained in the matrix resin act as a barier to water vapor permeating the resin to prolong the passage of the water vapor physically. Thus, the flakes serve to enhance the resistance of the lining to corrosion and water vapor diffusion.
Up to this time, flake lining has been applied by troweling or spraying. However, the application of flake lining by troweling has disadvantages in that the application necessitates a skilled worker, that the applicability is so poor as to result in an increased number of steps and that the lining thickness is so nonuniform and large owing to the nature of the application method that the lining tends to cause crack or peeling. Further, in the flake lining to be applied by troweling, relatively large flakes having a diameter of 100 to 800 .mu. are generally used, so that a compound for the lining comprising a resin and such flakes is too viscous to be deaerated in the kneading thereof. Therefore, the resulting lining exhibits a wide scatter in performances disadvantageously.
On the other hand, the application of flake lining by spraying has also disadvantages in that a compound for the lining contains relatively small flakes having a diameter of 20 to 200 .mu., so that the resulting lining film exhibits a high water vapor permeability and that the lining thickness is nonuniform owing to the nature of the application method to result in lowered lining performances. Furthermore, it is impossible to enhance the flake content of the compound to be applied by spraying because the viscosity of the compound must be generally 50 Poise or below and therefore the flake content thereof must be generally 20 to 30%. Namely, such a compound containing flakes in an amount exceeding 30% is too viscous to be sprayed, so that the resulting lining exhibits an enhanced water vapor permeability.
Further, in the application of flake lining by spraying, the flakes dispersed in a matrix resin are blown by spraying against a substrate, so that it is difficult to arrange the flakes in a state nearly parallel to the substrate. Furthermore, the use of larger flakes is impossible because they cause clogging of a nozzle.